Preparing to submit his mandatory letter of resignation to the pope, Cardinal Francis George named a new chief operating officer for the archdiocese on Tuesday, and announced other key changes to local governance.

The Rev. Peter Snieg will become moderator of the curia, the top administrative position in the archdiocese, starting July 1.

For the past 12 years, Chancellor Jimmy Lago has assumed those responsibilities, a function usually reserved for a priest. Lago's term as chancellor ends June 30.

Overseeing more than a dozen departments -- including evangelism, finances and schools — Lago has been one of the most influential laymen in the nation's Catholic hierarchy and the most powerful parishioner appointed by the cardinal in his 2.3 million-member flock.

In the 1970s, Lago helped launch the Catholic Conference, the political arm of Illinois’ Catholic bishops. In 1996, he became executive director of Catholic Charities.

The cardinal rewrote the chancellor’s job description when he appointed Lago to the position in 2000, consolidating the administrative duties of three other ecclesiastical offices under the chancellor’s oversight and spreading clerical duties around other departments.

Snieg currently serves as rector of St. Joseph’s Seminary at Loyola University. He will be replaced by the Rev. Paul SteinÖ, currently pastor of St. Sylvester Catholic Church.

George is required to submit a letter of resignation to Pope Benedict XVI on his 75th birthday. He celebrates that milestone on Monday. But he does not expect the pope to accept that resignation for at least two years.

Tuesday’s change to the archdiocese governance adds stability and continuity, George said, “so that the health of the Archdiocese as it transitions to a new Archbishop, whenever the Holy See makes that appointment, will be as strong as possible.”